Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/57

 much in quantity that the compound would sometimes be called a calcareous sandstone, while at others it would be described as a siliceous limestone. In the latter cases it is often dark-brown, gray, or even of a dark lead blue. The beds of mere limestone are rare, and those which I observed lie towards its upper boundary; they are of considerable size immediately in the vicinity of the Spar cave, which I described at the commencement of this paper. I think they are much more generally granular than compact, and some of them indeed resemble an aggregate of rounded grains, of the size of mustard seeds, not much differing from some of the oolites, but more compacted, and generally containing, besides these grains, crystallized platy particles. These strata are intersected in a remarkable manner by trap veins; but I shall defer the consideration of those to that which I conceive their proper place, the last in the history of the rocks.

The geographical chasm which intervenes between this and the remaining portions of white sandstone found in Sky is such, the want of accompanying strata so general, and the absence of characteristic indications in the internal composition so great, that I feel quite unable to determine the nature and connections of these detached portions. If any thing can be drawn from such indications as they present, they seem rather to prove that the sandstones which are found at Portree and in the northern parts of the island, appertain to strata different from those last described; but the remarks I have already made on the discontinuity of the limestone and the blue quartz rock, render me diffident in admitting any evidence respecting continuity of stratification, or the reverse, without access to proofs of a more decided nature.

White sandstone is to be found in many places on the eastern coast of the island, and is readily visible at Portree, where it alternates